BuddyPress

I’ve to manage a community of young children. I disabled the ability for them (“subscribers”) to create a group in BuddyPress Settings.
When a child wants to belong to a group, he/she posts a mention to “@admin” asking to become a member of Group X, right.

Problem is: How can I, as the administrator from within the Dashboard, make the child a member of the requested group?
Thanks.

Have you tried this plugin yet?

http://wordpress.org/extend/plugins/bp-group-management/

Yes I have, thanks. It just allows me to give (or remove) group admin rights to a member.

Note: I’m using BuddyPress’ last version.